High-dose atropine had the same effect on AL in highly myopic children with or without a known monogenetic cause. Photo: Getty Images.
Myopia can be inherited in a Mendelian fashion, as the genes responsible has a fairly strong heritability. Atropine has been shown to be effective against myopia progression in numerous studies; a recent trial looked into the effectiveness of atropine for reducing eye growth in Mendelian myopia in both children and mice and found that the treatment reduced axial length (AL).
Children were matched for age and AL in their first year of treatment. Annual AL progression rate was the outcome and rates were compared with percentile charts of an untreated general population. Mice were treated daily with 1% atropine in the left eye and saline in the right eye, from postnatal days 30 to 56.
Although progression rates during treatment were high in both groups, they appeared to be lower than the rates estimated from charts of uncontrolled eye growth. This assumption was validated in the mouse model.
“Contrary to the human eye, the mouse eye has a very small vitreous chamber, a wide anterior chamber and a large and rigid lens,” the authors explained. “This difference in ocular biometry between the species might explain why atropine predominantly affected the growth of the anterior chamber in mice, whereas it mostly affects the growth of the vitreous chamber in humans.”
To rule out a change in dimensions due to the cycloplegic effect of atropine, ocular biometry was measured shortly after application, and no immediate changes took place, indicating that the measured changes over time were true differences in AL growth, the authors noted. “Whether our observed findings in mice […] may be generalized to atropine treatment in all Mendelian myopia is uncertain,” the authors explained. “Similar to our results in children, atropine in mice may be a more effective inhibitor of eye growth for some genetic drivers than others.”
The researchers concluded, “The similarity in results in both these species strongly suggests that atropine can have merit in counteracting fast progressive myopia in monogenic ocular syndromes.”
Meester-Smoor MA, Thiadens AAHJ, Tan E, et al. Myopia control in Mendelian forms of myopia. Ophthalmic Physiological Opt. February 8, 2023. [Epub ahead of print].